I love Jamil's Whirlpool immersion chiller idea. From what I gather, the perks are killing two birds with one stone: chilling and whirlpool/trub removal.

Here's my question. Does it have to be an Immersion Chiller? Why couldn't you use a different type of chiller, like a CFC or even plate? I'd like to use a CFC, but recirculate to get the whirlpool effect. The reason that I prefer a CFC is that I'll be using it as HERMs a heat exchanger as well, so one less piece of equipment means less to clean, and possibly money savings.

Seems like most people run the hot wort through the CFC and directly into the fermentor. Wouldn't recirculation be beneficial, to get a whirlpool going? Am I missing something?

Yes your idea would work well and you would receive the added benefit of chilling the full wort volume faster. This gives you more retention of volatile hop compounds near the end of the boil for better aroma and flavor.

I have a plate chiller and recirculate back into the kettle. This seems like it would cool it quicker, but in reality, I timed it each way and it was basically the same. I suppose someone who knows more about thermodynamics could explain it, but it kinda makes sense bcs you are using the same amount of chiller water*. I do a hybrid now - I recirculate and capture this chill water for cleaning - usually gets to just under 100 or so. Then I use my MLT to recirculate ice water through the chiller as I drain into fermenter, I trade out frozen water bottles in it. This usually gets me into the 60's in about 15 minutes total chill time.

*this may be because a plate chiller is more efficient than an immersion chiller anyway??? (ie maximum surface area)

I am still working out some of the kinks, but here is what I did with my last batch.
I have a 1/2" CFC that can move a huge amount of hot wort at full pump speed, but I have to restrict the flow to get maximum chilling (Full discussion to follow someday when I get around to it)
I ran it full speed through the CFC into my HLT and let the whirlpool form there. That got the full 10 gallons down to about 85 deg in less than 5 min.
I got an OK whirlpool but need to build a little jet (a la Jamil) to get a really good one.
I then ran it through the CFC again into the two carboys at 65 deg. I think with some tweaking I can get the whole chilling process down to 15-20 minutes for a 10 gallon batch and have the whirlpool. That would include a non-DMS-forming break in the middle to let the cone form.
Cheers

I have a plate chiller and tried recirculating back into the kettle with a pump. This process takes MUCH LONGER (and far more cooling water) than pumping straight into the fermenter. When I pump straight from the boil to the fermenter without recirculating, I can cool the entire boil in less than five minutes. When I recirculate, it takes over 30 minutes!

I would have expected recirculation to take slightly longer, for two reasons: 1) the boil kettle has to be cooled along with the wort when recirculating, but not when going straight. 2) the pump has a greater head to work against when recirculating than when going to the fermenter. But both of these reasons should not account for a 7x increase in cooling time!

I don't know what I'm doing wrong here. I tried it with plain water to remove the hops and sugars from the equation, and I got the exact same result. I have a Thrumometer on the output of the plate chiller, so I know that the boiling liquid is being cooled to 65F from the start. The plate chiller is not even being used to its full potential: I can tell because most of the chiller is not even hot. When the chiller is being taxed (i.e. because the cooling water's temperature is too high), the chiller gets hot. But in my whirlpool I don't even have to turn my tap up very far in order to get the boiling liquid down to 65F.

I suspect that my recirculation pump might be underpowered. I am certainly not getting enough whirlpool action from it to create a cone in the fermenter. I have to manually stir in order to get that.

Until recently I recirc'ed with a CFC. It works just fine. The major downside, IMO, is that you're considerably restricting the flowrate of the pump forcing it through 25+ feet of tubing, which in turn reduces your whirlpool speed, which also reduces the effectiveness of the whirlpool. It's still effective enough to get a decent trub cone in my setup.

I'm considering getting a significantly more powerful pump just for whirlpooling. If you can really get that wort moving for a few minutes, the trub cone is impressive.

I pump through a CFC back to the kettle in a continuous loop and I have no trouble at all getting a good whirlpool going. My DIY CFC presents very little restriction to the flow as it is made from 20 ft of 1/2" ID rigid pipe. There seems to be some confusion about the whirlpool term. IMO, there are two distinct objectives with this method. One would be to cool the entire volume of wort as rapidly as possible and the second to form a debris cone. The chilling procedure requires that the wort be continuously and well mixed for optimum performance. Once chilled, you only need to stop pumping and allow the debris to settle. It's best to allow 15-30 minutes for this to happen. My point is that whirlpooling for chilling purposes is really just keeping the wort mixing while whirlpooling for debris cone formation is a separate operation and the debris won't drop out completely until the whirlpool has slowed to a stop.